This fine photo of an Osprey carrying a fish is the work of avid naturalist and photographer Shiyang (Edwin) Wu, who also brought us the rare Common Poorwill (Phalaenoptilus nuttallii) and the elusive Sierran Tree Frogs. Shiyang, a Cal molecular biology student, explains that he saw this bird on July 14 over the North Basin, and that it had been pursued by crows, but it outwinged them.
The Osprey (Pandion haliaetus) is native to California but is also seen in every continent except Antarctica. It’s one of the very few species of birds that’s almost identical wherever in the world it’s found. This bird is specialized for catching fish. Its outer toes are reversible so that it can grasp a fish with two toes on each side. The toes have very sharp edges and the scales on the talons point backward, the better to hold on to slippery fish in flight. The Osprey can close its nostrils when underwater, and its plumage is oily to let its feathers shed water quickly. Its eyes are adapted to viewing fish underwater from above, and the bird can correct for refraction as it dives. Fish make up at least 99 percent of its diet.
The Osprey will catch and eat any kind of fish that swims at or near the surface. The fish in the photo, Shiyang conjectures, is probably a jack silverside (Atherinopsis californiensis). The bird typically carries its prey to a high perch to eat it, but may also be carrying it to a nest to feed its hatchlings.
Several dozen pairs of Osprey have been breeding in the San Francisco Bay Area. Two of their nests have webcams installed; view them here. Thank you, Shiyang, for sharing this excellent photo.